As you can see from the example above delta makes no real distinction between
proprety upadate and property addition. Try to think of additions as an update
from undefined to whatever it's being updated to.

Patch fuction takes a hash and a delta and returns a new hash which is
just like orginial but with delta applied to it. Let's apply delta from the
previous example to the first hash from the same example

var patch =require("diffpatcher/patch")

patch({ a:{ b:1}, c:{ d:2}},// hash#1

{// delta

a:{

b:null,// -

e:3// +

},

c:{

d:4// ±

}

})

// => { a: { e: 3 }, c: { d: 4 } } // hash#2

That's about it really, just diffing hashes and applying thes diffs on them.